This invention relates to a radio frequency antenna and mixer system composed of a plurality of antennae and associated mixers, especially suitable for fabrication on a substrate utilizing semiconductor fabrication techniques.
Imaging systems are designed for detecting or "viewing" a scene and then reproducing it on some type of display device. For example, existing imaging systems include radar systems, infrared night vision scopes, and the like.
Typically, such systems have operated at electromagnetic frequencies outside of the millimeter-wave portion of the spectrum, i.e., not using electromagnetic energy having a wavelength of between ten millimeters and one millimeter, for frequencies of between 30 GHz and 300 GHz. Problems with lower frequency imaging systems, such as microwave radar systems, include lack of resolution. Problems with higher frequency imaging systems, such as infrared night vision scopes, include the difficulty of signals in this frequency range penetrating most fog, smoke, haze, rain, etc., and therefore the inability to produce a clear image under such circumstances.
It has been recognized that the use of millimeter-wave imaging systems, if they could be constructed in a compact, lightweight, inexpensive fashion, would provide a number of advantages including the ability of signals in this frequency range being able to penetrate poor atmospheric conditions, while also providing high image resolution. One problem in implementing compact, lightweight, inexpensive millimeter-wave imaging systems has been the lack of technologies and component parts which could operate effectively at millimeter-wave signal frequencies.
An example of one such component part or subsystem is an antenna and mixer array for intercepting radio frequency signals and processing the same for ultimate reproduction of the image represented by the signals. In particular, reflected or naturally emitted radio frequency signals from a target object would be detected by an array of receivers, including an array of antennae, the frequency of the received signals would be down-converted to an intermediate frequency, and then such intermediate frequency signals would be processed, using digital signal processing techniques to form an image of the target. Little, if anything, has been done to provide an antenna and mixer array in a fully solid state configuration, for operating in the millimeter-wave range.
It is an object of the invention to provide a radio frequency antenna and mixer array for receiving a plurality of radio frequency signals and for developing intermediate signals therefrom, using circuitry capable of operating in the millimeter-wave range of the electromagnetic signal spectrum.
It is another object of the invention to provide such an array which may be readily fabricated on a semiconductor substrate using semiconductor fabrication techniques.
It is also an object of the invention to provide such an array which is compact, lightweight and relatively inexpensive.
It is a further object of the invention to provide such an array in which inter-component electrical signal interference is minimized, and which allows for separate outputs for each antenna/mixer combination.